Ariewitz



April 14, 1964 D. ARIEWITZ VOLUME CONTROLS FOR FANS Filed Aug. 16, 1562 United States Patent Ofi ice 3,128,938 Patented Apr. 14, 1964 3,128,938 VOLUME CONTROLS FOR FANS Daniel Ariewitz, Framingham, Mass, assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa, a corporation of Pennsylvania Filed Aug. 16, 1962, Ser. No. 217,338 3 Claims. (Cl. 230-114) This invention relates to fans, and relates more particularly to diametral flow fans.

The most commonly used fan having a centrifugal rotor has a scroll-shaped casing with an axial inlet and a tangential outlet. Such casings are relatively large, and for some duties where space is limited, so-called diametral flow fans having smaller casings are used. In a diametral flow fan, the air or other gas being handled enters a centrifugal rotor cross-wise instead of axially. It is generally agreed that the rotor of such a fan generates a vortex near its cut-off, and that the flow of air through the fan is induced by the vortex.

The most efiicient method of varying the output of a fan is by spin inducing vanes as disclosed in the US. patents of H. F. Hagen, Nos. 1,846,863 and 1,989,413. Such a method requires that the fan have an axial inlet which a diametral flow fan does not have. A damper can be used in the inlet or outlet of the fan to adjust its output, but when such a damper is adjusted to reduce flow, there is no corresponding reduction in power consumption as where spin vanes are used. Another disadvantage of using a damper is that near its block-tight position there is unstable operation and surging.

This invention reduces the output of a diametral flow fan from maximum to an intermediate value by moving the cut-oif of the fan further from the rotor. This shifts the vortex nearer the center of the rotor, with more circulation and less flow through the fan outlet. The reduction in output thus achieved is efi'icient in that the power consumption is correspondingly reduced, but the flow cannot be reduced to zero. For reducing the fiow to zero, a damper plate is placed in the outlet of the fan, and is connected to a cut-off plate for movement therewith, the damper plate being moved towards closed or block-tight position when the cut-off plate is moved further from the rotor. During the preliminary adjustment of the two plates, the output reduction is accomplished principally by the cut-off plate. During the final adjustment of the two plates, the output is reduced to or near Zero by the damper plate. The loss in efficiency caused by the use of the damper plate is not substantial since in most cases the range of reduction required is within that provided principally by the cut-off plate, in which range the resistance to fiow of the damper plate is insignificant. By the time the damper plate is adjusted to near block-tight position, the energy has been so reduced by the cut-oii plate that there is stable operation.

A feature of this invention is that a differential linkage is provided between the cut-off and damper plates so that the degree and rate of change of each can be adjusted to suit operating conditions.

An object of this invention is to provide an effective, efficient volume control for a diametral flow fan.

Another object of this invention is to control the output of a fan having a centrifugal rotor by shifting the position of its cut-off, and by throttling its outlet.

This invention will now be described with reference to the annexed drawings, of which:

FIG. 1 is a side view, partially section, of a diametral flow fan embodying this invention, and

FIG. 2 is an end view partially in section, of the fan, looking at its outlet end.

A casing has an air inlet 11 and an air outlet 12,

and extends around a rotor 13 having forwardly curved blades 14. The rotor 13 is attached to a shaft 15 supported in bearings 16 attached to side walls 17 of the casing. There is a converging inlet passage 18 as is usual in diametral flow fans.

For adjusting the output of the fan, a shaft 20 is journalled in sleeves 25 in the walls 17 at about the level of the top of the outlet 12, and is attached at one end to a manually operated handle 21. A damper plate 22 is attached directly to the shaft 20 for rotation therewith. A cut-off plate 24 is attached at its ends to the sleeves 25. A cut-oif link 26 having three spaced-apart holes 27 extending therethrough along its longitudinal center, is attached at its lower end to the left sleeve. A common link 29 is pivoted at its upper end on a pin 30 extending outwardly from the adjacent side wall 17, and has a pin 31 extending from its lower end into a central one of five holes 32 which are spaced-apart along the longitudinal center of damper link 34. The damper link 34 is fixedly attached at its lower end to the shaft 20. The link 29 has a pin 36 extending from its center into a central one of the holes 27.

The damper plate 22 and the cut-oft plate 24 are shown by solid and dashed lines in their normal, maximum output positions, with a cut-off space C between the inner end of the plate 24 and the rotor 13. The plates 22 and 24 are shown by dash-dot lines in their zero volume positions, with a cut-off space C between the inner end of the plate 24 and the rotor 13.

The handle 21 can be rotated in a clockwise direction to reduce the output of the fan. Rotation of the shaft 20 by the handle 21 rotates the damper link 34 which rotates through the pin 31, the common link 29 which rotates through the pin 36 the cut-off link 26, which rotates through the left sleeve 25 the cut-off plate 24 to move its inner end further from the rotor 13. The damper plate 22 is rotated directly by the shaft 20 towards its fullyclosed or zero volume position. Thus, the damper plate and the cut-off plate are moved together by the handle 21 to reduce or increase the output of the fan.

By placing the pins 31 and 36 in other ones of the holes 32 and 27 respectively, in the links 34 and 26 respectively, the degree and the rate of change of the movement of the cut-off plate relative that of the damper plate can be adjusted to suit different operating conditions.

When the handle 21 is adjusted from its maximum volume position towards its zero volume position, during the first portion of this movement, the volume reduction is accomplished principally by movement of the cutoff plate 24. The action of the cut-off plate in reducing the volume diminishes and finally stops as the handle 21 approaches zero volume position, while the action of the damper plate in reducing volume increases as the handle 21 approaches zero volume position. Thus, a complete range of adjustment is provided with an efficiency much higher than if the damper alone was used to reduce output.

A cut-off plate or cut-01f plate means where referred to in the annexed claims, is defined as a transition plate or transition plate means respectively, which converts spinning flow around the rotor of a fan into straight line flow at the fan outlet.

What is claimed, is:

1. A fan having a casing with a tangential air outlet and an air inlet, a centrifugal rotor supported for rotation within said casing between said inlet and outlet, cut-off plate means and damper means connected and supported for concurrent rotation within said casing between said rotor and outlet, and means for rotating said cut-off plate and damper means, said cut-off plate means having an inner end rotatable towards and from said rotor when said damper means is rotated towards open and closed position respectively, said inner end being nearest said rotor when said damper means is in open position and being rotated further from said rotor when said damper means is rotated towards closed position.

2. A fan having a casing with a tangential air outlet and an air inlet, a centrifugal rotor supported for rotation within said casing, a cut-off plate supported for rotation within said casing, said plate having an inner end rotatable towards and from said rotor, a damper plate supported for rotation towards open and closed positions within said outlet, means connecting said plates so that when said damper plate is rotated towards closed position said inner end of said cut-off plate is rotated further from said rotor, and means for rotating said damper plate.

3. A fan having a casing with a tangential air outlet and an air inlet, a centrifugal rotor supported for rotation within said casing, a cut-off plate supported for rotation within said casing, said plate having an inner end rotatable towards and from said rotor, a damper plate supported for rotation towards open and closed positions within said outlet, means connecting said plate so that when said damper plate is rotated towards closed position said inner end of said cutoff plate is rotated further from said rotor, adjusting means connected to said means for varying the degree of movement of one of said plates relative to the other one of said plates, and means for 10 rotating said damper plate.

References Cited in the file of this patent UNITED STATES PATENTS 15 960,815 Carlisle June 7, 1910 2,282,015 Williams May 5, 1942 2,511,382 Stonehouse June 13, 1950 2,719,666 Hollingsworth Oct. 4, 1955 2,721,704 Patrick Oct. 25, 1955 

1. A FAN HAVING A CASING WITH A TANGENTIAL AIR OUTLET AND AN AIR INLET, A CENTRIFUGAL ROTOR SUPPORTED FOR ROTATION WITHIN SAID CASING BETWEEN SAID INLET AND OUTLET, CUT-OFF PLATE MEANS AND DAMPER MEANS CONNECTED AND SUPPORTED FOR CONCURRENT ROTATION WITHIN SAID CASING BETWEEN SAID ROTOR AND OUTLET, AND MEANS FOR ROTATING SAID CUT-OFF PLATE AND DAMPER MEANS, SAID CUT-OFF PLATE MEANS HAVING AN INNER END ROTATABLE TOWARDS AND FROM SAID ROTOR WHEN 